The present invention relates to a free fall simulator including a self-contained air circuit and an aeration device for a wind tunnel, in particular a free fall simulator.
A free fall simulator including a self-contained air circuit is an apparatus adapted to maintain a person in a hovering position in a (as a rule controllable) vertically ascending air stream which flows through a hover chamber. After exiting an upper opening of the hover chamber, the air stream is redirected to a lower opening of the hover chamber via an air guide channel in such a manner that a self-contained air circuit is formed.
A typical effect of these so-called closed-type free fall simulators is that, due to pressure losses, the air within the simulator is heated which entails various problems. On the one hand, the overheating of the air may be perceived as unpleasant by the persons using the simulator, or in case of a considerable overheating, may even be injurious to health. On the other hand, the heating of the air results in a reduction of the air density which in turn decreases the force keeping the hovering person in equilibrium. In total, an increased control expenditure is necessary due to the combination of fans frequently arranged next to each other and the aerating means which can be opened as required.
Several approaches have been already proposed for reducing the disadvantages just described.
EP 19 64 776 A1 shows a free fall simulator in which persons can be lifted in a vertical area by means of a generated air stream. The curved recirculation lines are in this case constructed from materials which exhibit a high heat conductivity. In addition, a cooling-water circuit moderates the temperature within the free fall simulator. Such a temperature regulation is associated with a limited material choice and complicated.
Another way for reducing the above-indicated general problems of closed-type free fall simulators is shown in EP 1 539 572 B1. Here, a free fall simulator for various learning, educating and training purposes for parachutists or certified competitors is described. In order to reduce the overheating of the air due to the operation of propeller fans, a fresh air intake is provided in an upper part of a dome. A plurality of extractor fans ensure the aspiration of air and further allow the temperature of the flight simulator to be controlled. Here, it is hence a so-called active air exchange, which means that additional machines, namely the extractor fans, are used to guarantee the air exchange. This leads to increased energy consumption which, together with the manufacturing costs for the extractor fans, requires considerable additional financial expenditures.
A so-called passive air exchange is described in WO 2006/012647 A2. This prior art free fall simulator is of an essentially rectangular configuration, with a hover chamber being provided in a first vertical section followed by a downstream first horizontal section in which two fans are arranged for generating an air stream. The first horizontal section is followed by a second vertical section serving the purpose of redirecting the air stream toward a bottom area. In this second vertical section, an inlet door and an outlet door are installed so as to narrow the flow cross-section and form a jet. A pressure gradient is thereby formed between the inner space and the outer space of the tunnel so that air exchange takes place and the temperature is thereby moderated. A disadvantage of this free fall simulator is that due to the constriction of the flow cross-section by the inlet door and outlet door, the flow speed is further increased in the area of these doors resulting in increased air friction with additional heat generation. Moreover, the inlet and outlet doors are exposed to extremely high stress due to their orientation into the air stream.